Evaluation and assessment of the efficacy of an abatement strategy in a former lead smelter community, Boolaroo, Australia.

Abstract

This study examines the recent soil Lead Abatement Strategy (LAS) in Boolaroo, New South Wales, Australia, that was designed to "achieve a reduction in human exposure to lead dust contamination in surface soils". The abatement programme addressed legacy contamination of residential areas following closure of lead smelting operations in 2003 at the Pasminco Cockle Creek Smelter (PCCS). The principal objective of the LAS was to "cap and cover" lead-contaminated soils within the urban environment surrounding the PCCS. Soil lead concentrations of 2500-5000mg/kg were scheduled for removal and replacement, while concentrations between 1500 and 2500mg/kg were replaced only under limited circumstances. To date, there has been no industry, government or independent assessment of the clean-up programme that involved >2000 homes in the township of Boolaroo. Thus, by measuring post-abatement soil lead concentrations in Boolaroo, this study addresses this knowledge gap and evaluates the effectiveness of the LAS for reducing the potential for lead exposure. Soil lead concentrations above the Australian residential soil health investigation level value for residential soils (300mg/kg) were identified at all but one of the residential properties examined (n=19). Vacuum dust samples (n=17) from the same homes had a mean lead concentration of 495mg/kg (median 380mg/kg). Bio-accessibility testing revealed that lead in household vacuum dust was readily accessible (% bio-accessible) (mean=92%, median=90%), demonstrating that the risk of exposure via this pathway remains. Assessment of a limited number of properties (n=8) where pre-abatement soil lead levels were available for comparison showed they were not statistically different to post-abatement. Although the LAS did not include treatment of non-residential properties, sampling of community areas including public sports fields, playgrounds and schools (n=32) was undertaken to determine the contamination legacy in these areas. Elevated mean soil lead concentrations were found across public lands: sports fields=5130mg/kg (median=1275mg/kg), playgrounds and schools=812mg/kg (median=920mg/kg) and open space=778mg/kg (median=620mg/kg). Overall, the study results show that the LAS programme that was dominated by a "cap and cover" approach to address widespread lead contamination was inadequate for mitigating current and future risk of lead exposures.